Solid-state imaging device and electronic equipment

ABSTRACT

A solid-state imaging device includes a pixel unit in which a plurality of pixels converting physical quantities into electric signals are arranged in a two-dimensional shape, a vertical signal line for reading signals from the pixels, and column circuits arranged corresponding to columns of the pixel unit and collecting the signals from the vertical signal line at the inside of the pixel unit.

CROSS REFERENCES TO RELATED APPLICATIONS

This is a Continuation of application Ser. No. 14/738,147, filed on Jun.12, 2015, which is a Continuation of application Ser. No. 13/317,377,filed on Oct. 17, 2011, now U.S. Pat. No. 9,087,758, issued on Jul. 21,2015, and contains subject matter related to Japanese Patent ApplicationJP 2010-252587, filed in the Japanese Patent Office on Nov. 11, 2010,the entire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to a solid-state imaging device, andparticularly to a CMOS solid-state imaging device and electronicequipment such as a camera having the solid-state imaging device.

As a solid-state imaging device (an image sensor), a CMOS solid-stateimaging device is famous in the art. The CMOS solid-state imaging deviceis used for various portable terminals such as digital still cameras,digital video cameras, and camera-embedded cellular phones.

In a general CMOS solid-state imaging device, a circuit for receiving asignal of a pixel and performing CDS (collated double sampling) or AD(analog/digital) conversion thereto is generally provided to every pixelcolumn at an end of a pixel unit in which a plurality of pixels arearranged, as disclosed in Japanese Unexamined Patent ApplicationPublication No. 2003-18471. This circuit is called a column circuit heresince it is provided to every column.

As another CMOS solid-state imaging device, also famous is a solid-stateimaging device in which a circuit for receiving a pixel signal andperforming CDS or AD conversion is provided to each pixel or eachsection of a plurality of pixels, not to each pixel column, on thepremise that a semiconductor chip is laminated, as disclosed in JapaneseUnexamined Patent Application Publication No. 2006-49361. In the casewhere a pixel signal is received for each section of a plurality ofpixels, as shown in a schematic view of FIG. 15A, in a pixel unit 201 inwhich the plurality of pixels are arranged in a two-dimensional shape,the pixels are divided into a plurality of sections so that a regionincluding a plurality of pixels is set to one section 202. In addition,each pixel section 202 is configured to receive a signal from onecircuit as above. In each pixel section 202, pixel signals are read inorder as shown by a solid line arrow 203 and a dashed line 204. Signalsare read simultaneously at every pixel section 202.

Incidentally, as related technologies of the CMOS solid-state imagingdevice, a CMOS solid-state imaging device in which a semiconductor chipis laminated in a rear-side incident type is disclosed in InternationalPublication No. WO 2006/129762 and Japanese Unexamined PatentApplication Publication No. 2007-013089.

SUMMARY

However, in the CMOS solid-state imaging device in which a columncircuit is provided to each pixel column, a long vertical signal lineruns on the pixel unit, and the column circuit receives a signal at itsend. For this reason, the signal from a pixel at the upper end in thevertical direction of the pixel unit is in a different level from thesignal from a pixel at the lower end due to the voltage drop caused bythe wiring resistance of the vertical signal line. This difference insignal level is offset and removed by CDS, but somewhat shaded since theoffset suppression ratio of CDS is not infinite. In addition, the offsetmakes the operation range of CDS narrower or becomes an obstacle againstthe decrease of voltage.

In addition, in the case where the column circuits are provided to bothupper and lower ends of the pixel unit, the offset changes depending onwhether a signal is read by a pixel at the upper column circuit or thelower column circuit even though pixels are located substantially at thesame location, which results in a difference in properties. This problemis becoming more serious due to recent increases in the pixel currentdue to the speed increases in the CMOS solid-state imaging device,increasing the pixel unit due to a growth in size, by making wiringsthinner due to pixel miniaturization, or by applying strict requirementson the image quality.

In this point, in the method for providing a circuit for performing CDSor AD conversion for each pixel or each section of a plurality ofpixels, the size of the circuit is determined in length and width bysize of the pixel or the section of a plurality of pixels. For thisreason, a necessary function may not be included, or the circuit mayhave a spare area which is wasted. In addition, in the case where acircuit is provided to each section of a plurality of pixels, unless amethod for ensuring simultaneity of the exposure time in a screen, whichis called global shutter, is used, when an object 206 moving in an arrowdirection 205 is imaged as shown in FIG. 15B, pixels in the upper halfpart of the pixel unit 201 are read later and pixels in the lower halfpart are read earlier as shown in FIG. 15C, resulting in distortedimaging of the moving object 206. The global shutter is necessary todeteriorate image quality or increase a pixel size.

The present disclosure has been made in view of such circumstances, andit is desirable to provide a solid-state imaging device which decreasesa voltage drop of a vertical signal line and improves image quality byimproving shading or the like.

It is also desirable to provide electronic equipment such as a camerahaving the solid-state imaging device.

According to an embodiment of the present disclosure, a solid-stateimaging device includes a pixel unit in which a plurality of pixelsconverting physical quantities into electric signals are arranged in atwo-dimensional shape, a vertical signal line for reading signals fromthe pixels, and column circuits arranged corresponding to columns of thepixel unit and collecting the signals from the vertical signal line atthe inside of the pixel unit.

In the solid-state imaging device according to the embodiment of thepresent disclosure, since the signals of pixels are collected to thecolumn circuits not from an end of the pixel unit but from the inside ofthe pixel unit from the vertical signal line, the voltage drop caused bythe wiring resistance of the vertical signal line decreases.

According to the embodiment of the present disclosure, a solid-stateimaging device includes an upper substrate having a pixel unit in whicha plurality of rear-side incident type pixels converting physicalquantities into electric signals are arranged in a two-dimensionalshape; and a lower substrate facing the upper substrate and having aplurality of column circuits arranged corresponding to columns of thepixel unit, wherein the upper substrate and the lower substrate areconnected at the wiring surface sides thereof, wherein a vertical signalline formed at the upper substrate and reading signals from the pixelsare connected to the column circuits of the lower substrate at a sidewhere the column circuits face each other in the vertical direction of asurface of the lower substrate, and wherein signals of the columncircuits are output to a side where the column circuits do not face eachother.

In the solid-state imaging device according to the embodiment of thepresent disclosure, since the vertical signal line reading signals frompixels and the column circuits of the lower substrate are connected at aside where the column circuits face each other in the vertical directionof the surface of the lower surface, the voltage drop caused by thewiring resistance of the vertical signal line decreases.

According to an embodiment of the present disclosure, the electronicequipment includes a solid-state imaging device; an optical system forleading incident light to a photoelectric conversion unit of thesolid-state imaging device; and a signal processing circuit forprocessing an output signal of the solid-state imaging device, whereinthe solid-state imaging device is the solid-state imaging deviceaccording to the present disclosure.

In the electronic equipment according to the embodiment of the presentdisclosure, since the solid-state imaging device according to thepresent disclosure is provided, the voltage drop caused by wiringresistance of the vertical signal line decreases when the signals ofpixels are collected from the vertical signal line to the columncircuits.

According to the solid-state imaging device of the embodiments of thepresent disclosure, since the voltage drop caused by the wiringresistance of the vertical signal line decreases when a signal of apixel is read, it is possible to improve image quality, for exampleimproving the shading caused by the voltage drop. Therefore, it ispossible to provide high-quality solid-state imaging device.

According to the electronic equipment of the embodiment of the presentdisclosure, in the solid-state imaging device, since the voltage dropcaused by the wiring resistance of the vertical signal line decreaseswhen a signal of a pixel is read, it is possible to improve imagequality, for example improving the shading caused by the voltage drop.Therefore, it is possible to provide high-quality electronic equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a first embodiment of a solid-stateimaging device according to an embodiment of the present disclosure;

FIGS. 2A and 2B are schematic plan views showing a first semiconductorchip and a second semiconductor chip according to the first embodiment;

FIG. 3 is a block diagram showing a connection relation between pixelsand a column circuits in an embodiment of the present disclosure;

FIG. 4 is an equivalent circuit diagram showing one example of a unitpixel according to the embodiment of the present disclosure;

FIGS. 5A to 5E are diagrams illustrating operations of the solid-stateimaging device according to the first embodiment;

FIG. 6 is a schematic view showing a second embodiment of thesolid-state imaging device according to the present disclosure;

FIGS. 7A and 7B are schematic plan views showing a first semiconductorchip and a second semiconductor chip according to the second embodiment;

FIGS. 8A to 8E are diagrams illustrating operations of the solid-stateimaging device according to the second embodiment;

FIG. 9 is a schematic view showing a third embodiment of the solid-stateimaging device according to the present disclosure;

FIGS. 10A and 10B are schematic plan views showing a first semiconductorchip and a second semiconductor chip according to the third embodiment;

FIGS. 11A to 11D are diagrams illustrating operations of the solid-stateimaging device according to the third embodiment;

FIG. 12 is a schematic cross-sectional view showing a solid-stateimaging device according to a modified example of the presentdisclosure;

FIG. 13 is a schematic view showing electronic equipment according to afourth embodiment of the present disclosure;

FIG. 14 is a schematic view showing one example of a CMOS solid-stateimaging device; and

FIGS. 15A to 15C are schematic views showing configurations of existingsolid-state imaging devices and images obtained by imaging a movingobject.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described.The description will be provided in the following order.

1. Example of a schematic configuration of a CMOS solid-state imagingdevice

2. First embodiment (an example of the solid-state imaging device)

3. Second embodiment (an example of the solid-state imaging device)

4. Third embodiment (an example of the solid-state imaging device)

5. Fourth embodiment (an example of the electronic equipment)

1. Example of a Schematic Configuration of a CMOS Solid-State ImagingDevice

First, for the understanding of the present disclosure, one example of aschematic configuration of a CMOS solid-state imaging device will bedescribed with reference to FIG. 14. The CMOS solid-state imaging device101 includes a pixel unit (a so-called imaging region) 103 having aplurality of pixels 102 provided with a photoelectric conversion unitprovided in a silicon substrate and regularly arranged in atwo-dimensional shape on a semiconductor substrate 111, and a peripheralcircuit unit. As the pixel 102, a unit pixel composed of onephotoelectric conversion unit and a plurality of pixel transistors maybe applied. In addition, as the pixel 102, a so-called pixel-sharingstructure where a plurality of photoelectric conversion units sharespixel transistors other than a transmission transistor may be applied.The plurality of pixel transistor may be configured with fourtransistors composed of a transmission transistor, a reset transistor,an amplification transistor and a selection transistor, or threetransistors where the selection transistor is excluded.

The peripheral circuit unit is configured with so-called logic circuitssuch as a vertical driving circuit 104, a column circuit 105, ahorizontal driving circuit 106, an output circuit 107 and a controlcircuit 108.

The control circuit 108 receives data instructing an input clock, anoperation mode or the like and outputs data such as internal informationof the solid-state imaging device. In addition, the control circuit 108generates a clock signal or a control signal which will become criteriaof operations of the vertical driving circuit 104, the column circuit105 and the horizontal driving circuit 106 based on a verticalsynchronizing signal, a vertical synchronizing signal and a masterclock. In addition, those signals are input to the vertical drivingcircuit 104, the column circuit 105, the horizontal driving circuit 106,and so on.

The vertical driving circuit 104 is, for example, composed of shiftregisters, selects a pixel driving wiring to supply a pulse for drivinga pixel to the selected pixel driving wiring, and drives pixels for eachrow. In other words, the vertical driving circuit 104 selectively scanseach pixel 102 of the pixel unit 103 for each row successively in thevertical direction. In addition, the vertical driving circuit 104supplies through a vertical signal line 109 a pixel signal based on thegenerated signal charge to the column circuit 105 according to theamount of light received in, for example, a photodiode which becomes aphotoelectric conversion element of each pixel 2.

The column circuit 105 is disposed to, for example, every column of thepixels 102 and performs signal pressing such as noise removal of asignal output from pixels 102 in one row for every pixel column. Inother words, the column circuit 105 performs signal processing such asCDS, signal amplification, and AD conversion in order to remove afixed-patterned noise inherent in the pixels 102. A horizontal selectionswitch (not shown) is installed to the column circuit 105 to beconnected to a horizontal signal line 110.

The horizontal driving circuit 106 is, for example, composed of shiftregisters and selects the column circuits 105 in order by successivelyoutputting horizontal scanning pulses so that a pixel signal is outputfrom each column circuit 105 to the horizontal signal line 110.

The output circuit 107 processes and outputs signals successivelysupplied from each column circuit 105 through the horizontal signal line110. For example, the output circuit 107 may perform only buffering orperform black level adjustment, column deviation correction, or variousdigital processes. The input/output terminal 112 exchanges signals withthe outside.

2. First Embodiment Example of the Solid-State Imaging Device

FIGS. 1 to 2B show the first embodiment of the solid-state imagingdevice according to the present disclosure. This embodiment is arear-side incident type CMOS solid-state imaging device, and FIGS. 1 to2B are schematic views of the whole configuration.

In the solid-state imaging device 1 according to the first embodiment,as shown in FIG. 1, a first substrate 2 having a pixel unit in which aplurality of pixels converting physical quantities into electric signalsare arranged in a two-dimensional shape and a second substrate 3 havingcolumn circuits are laminated and electrically connected through aconnection portion 4. In other words, the first substrate 2 includes, asshown in FIG. 2A, a pixel unit 6 in which a plurality of rear-sideincident type pixels 5 are arranged in a two-dimensional shape, and afirst semiconductor chip having a vertical driving circuit 7.Hereinafter, the first substrate 2 will be called a first semiconductorchip. The first semiconductor chip 2 is a so-called rear-side incidenttype CMOS image sensor chip. The second substrate 3 is, as shown in FIG.2B, configured as a second semiconductor chip including a column circuit11, a control circuit 12, a horizontal driving circuit 13, and a signalprocessing circuit 14 corresponding to an output circuit. Hereinafter,the second substrate 3 will be called a second semiconductor chip. Thefirst semiconductor chip (corresponding to an upper substrate) 2 ismounted in a flip-chip manner to the second semiconductor chip(corresponding to a lower substrate) 3 through a micro bump serving asthe connection portion 4 to configure the solid-state imaging device 1.Hereinafter, the connection portion 4 will be called a micro bump.

The first semiconductor chip 2 includes a pixel unit 6 in which aplurality of pixels, each having a photodiode (PD) serving as aphotoelectric conversion portion and a plurality of pixel transistorsare arranged in a two-dimensional shape, and a vertical driving circuit7 to the semiconductor substrate 8. The photodiode (PD) is formed toface the rear side of the semiconductor substrate 8, and the pixeltransistor includes a floating diffuser (FD) and is formed at thesurface side of the semiconductor substrate 8. The rear side of thesubstrate becomes a light receiving surface, and though not shown in thefigures, an anti-reflection film, a color filter, an on-chip lens and soon are laminated on the light receiving surface.

The vertical driving circuit 7 is connected to a pixel driving wiring 9which supplies a pulse voltage to drive the pixel 5. The pixel drivingwiring 9 is commonly connected to pixels 5 of each one row arranged inthe horizontal direction of the pixel unit, and, even though one wiringformed in the horizontal direction (the lateral direction) isrepresentatively shown in FIG. 2A, a plurality of pixel driving wirings9 are disposed as described below. In addition, a vertical signal line10 is disposed to pixels 5 of each column in the vertical direction ofthe pixel unit 6. The pixel driving wiring and the vertical signal lineare formed as a plurality of wiring layers disposed through aninterlayer isolation film at the surface side of the semiconductorsubstrate.

At the pixel unit 6 of the first semiconductor chip 2, the pixel drivingwiring 9 is selected by the vertical driving circuit 7, by the pulsevoltage supplied through the selected pixel driving wiring 9, the pixels5 of one row corresponding thereto are driven simultaneously, and thesignals of the pixels 5 are output to the vertical signal line 10.

The second semiconductor chip 3 includes, as shown in FIG. 2B, a columncircuit 11 formed at a center region of the surface side of thesemiconductor substrate 16, and horizontal driving circuits 13 [13A and13B] provided at both upper and lower sides of the column circuitregion. A control circuit 12 and a signal processing circuit 14 areformed at both right and left sides of the column circuit region. Thecolumn circuit 11 is installed according to the pixel column of thepixel unit 6 as much as the same number as the pixel columns. In otherwords, the numerical relation between the pixel columns of the pixelunit 6 and the column circuits 11 becomes 1:1. In the column circuit 11,for example, column circuits 11A corresponding to the odd number columnsof the pixel unit 6 are arranged at the upper end side in the horizontaldirection of the semiconductor substrate 16, and column circuits 11Bcorresponding to even number columns of the pixel unit 6 are arranged atthe lower end side in the horizontal direction of the semiconductorsubstrate 16.

In other words, the column circuits 11 [11A and 11B] are arrangedcorresponding to the pixel columns near the center of the pixel unit 6formed at the first semiconductor chip. In addition, the column circuits11A of odd number pixel columns disposed at the upper and lower locationin the vertical direction and the column circuits 11B of even numberpixel columns are arranged to face each other so that their inputterminals (corresponding to the micro bump 4) face each other. Since thecolumn circuits 11A corresponding to odd number pixel columns and thecolumn circuits 11B corresponding to even number pixel columns aredisposed at locations corresponding to odd number columns and evennumber columns of each pixel 5, they are arranged to be dislocated byone pitch of the pixel column in the horizontal direction. Each columncircuit 11 is formed to have a width d1 identical to the width d2 of twopixel columns of the pixel unit 6 (d1=d2). In addition, in the firstsemiconductor chip 2, the vertical signal line 10 reading signals ofpixels in odd number columns and the vertical signal line readingsignals of pixels in even number columns are connected at a side wherethe upper and lower column circuits 11A and 11B encounter in the secondsemiconductor chip 3.

As described above, the control circuit 12 receives data instructing aninput clock, an operation mode or the like and outputs data includinginformation of the solid-state imaging device. In addition, the controlcircuit 12 supplies necessary clocks or pulses to each component asbelow.

The column circuit 11 supplies a bias current to the pixel 5 andreceives a signal of pixels 5 in each column to perform CDS (collateddouble sampling: removal or processing of fixed-patterned noise), signalamplification or AD conversion to the signal.

The horizontal driving circuit 13 [13A and 13B] selects the columncircuits 11 in order and leads the signal to the signal processingcircuit. The signal processing circuit 14 processes and outputs thesignal. For example, the signal processing circuit 14 may perform onlybuffering or perform black level adjustment, column deviationcorrection, signal amplification, color-related processing or the like.

The first semiconductor chip 2 and the second semiconductor chip 3 areelectrically and mechanically connected through the micro bump 4 byarranging their surfaces where wirings are formed, namely wiringsurfaces of the pixels, to face each other. In the first semiconductorchip 2, a plurality of wiring layers are formed through an interlayerisolation film on a surface opposite to the light receiving surface ofthe semiconductor substrate 8 having the pixel unit 6. In the secondsemiconductor chip 3, a plurality of wiring layers are formed through aninterlayer isolation film on the surface of the semiconductor substrate16 where the column circuit 11, the horizontal driving circuit 13, thecontrol circuit 12 and the signal processing circuit 14 are formed. Themicro bumps 4 are formed at the first semiconductor chip 2 side, at thesecond semiconductor chip 3 side, or at both sides of semiconductorchips 2 and 3. In the drawings, the micro bump 4 is depicted only at thelower second semiconductor chip 3 side. The micro bump 4 connects thevertical signal line 10 of the pixel unit 6 to the column circuit 11.

In this example, the micro bump 4 is formed at the wiring surface of thesecond semiconductor chip 3, formed at locations where the columncircuit 11A corresponding to odd number columns of the pixel unit 6 andthe column circuit 11B corresponding to even number columns face eachother. Through the micro bump 4, the input terminal of each columncircuit 11 located near the center is electrically connected to thecenter portion of the vertical signal line 10 of the pixel unit 6. Thecolumn circuit 11 is disposed to face the vertical signal line 10 basedon the center portion of the pixel unit 6 in the vertical direction. Inother words, the column circuit 11 is disposed to face the verticalsignal line 10 based on the micro bump 4 near the center of the pixelunit 6 in the vertical direction. The micro bump 4 is also formed at alocation, not shown, around the second semiconductor chip 3, and powerand information about the driving of pixels are exchanged through themicro bump 4 formed around the second semiconductor chip 3.

The pixel 5 and the column circuit 11 are connected as shown in FIG. 3.Regarding the pixel unit 6 of the first semiconductor chip 2, aplurality of pixels 5 disposed in each column are connected to thevertical signal line 10. Meanwhile, in the second semiconductor chip 3,the column circuit 11 is formed corresponding to each pixel column. Inthe pixel unit 6, namely near the center of the pixel unit 6 in thisexample, the vertical signal line 10 and the column circuit 11 areconnected at the micro bump 4. Here, the column circuit 11 has aconstant current source 18 and an analog/digital converting circuit(ADC) 17. The constant current source 18 allows a bias current to flowthrough the pixel 5. The bias current flows from a power terminal in aselected pixel 5 through the vertical signal line 10 and the micro bump4 to a ground terminal in the constant current source 18. Theanalog/digital converting circuit 17 shares a node 19 of the micro bump11 with the constant current source 18, collects a voltage of the nodewhich is an output of the pixel, and performs analog/digital conversionthereto. In other words, in the column circuit 11, a path allowing abias current to flow to the pixel 5 and a path collecting a signal ofthe pixel 5 share the connection portion through the micro bump 4.

FIG. 4 shows an example of an equivalent circuit of the pixel. The pixelincludes a photodiode serving as a photoelectric conversion unit and aplurality of pixel transistors composed of a transmission transistorTr1, a reset transistor Tr2, an amplification transistor Tr3 and aselection transistor Tr4 in this example. The photodiode (PD) isconnected through the transmission transistor Tr1 to the floatingdiffuser (FD). The transmission transistor Tr1 transmits charges of thephotodiode (PD) (e.g., photoelectrons) to the floating diffuser (FD).The floating diffuser (FD) is connected to the gate of the amplificationtransistor Tr3. The amplification transistor Tr3 outputs a signalcorresponding to the potential of the floating diffuser (FD) to thevertical signal line 10 if the selection transistor Tr4 turns on. Thereset transistor Tr2 is connected to the floating diffuser (FD) anddischarges changes of the floating diffuser (FD) to a power wiring toreset the floating diffuser (FD). The equivalent circuit of the pixel 5is not novel but a general one. Three wirings 21, 23 and 22 respectivelyconnected to the gates of the transmission, selection and resettransistors Tr1, Tr4 and Tr2 correspond to the above pixel drivingwirings 9.

FIGS. 5A to 5D show operations of the solid-state imaging deviceaccording to the first embodiment, namely the flow of signals from thepixel. In the pixel unit 6 of the first semiconductor chip 2, signals ofthe pixels 5 are read by the vertical signal line 10 in the upwardsorder from a first pixel row to n^(th) pixel row. In the pixel unit 6,the signals of upper-half (upper) pixels 5 pass the vertical signal line10 in the order from the first pixel row to the m^(th) pixel row (seeFIGS. 5B and 5D), and are input to the column circuit 11 of the secondsemiconductor chip 3 through the micro bump 4 near the center of thepixel unit 6. In the pixel unit 6, the signals of lower-half (lower)pixel 5 pass the vertical signal line in the order from the m+1^(th)pixel row to the n^(th) pixel row (see FIGS. 5C and 5D), and are inputto the column circuit 11 of the second semiconductor chip 3 through themicro bump 4 near the center of the pixel unit 6. Here, the signals ofodd number column pixels 5 are input to the upper column circuit 11A(see FIG. 5E), and the signals of even number column pixels 5 are inputto the lower column circuit 11B (see FIG. 5E). The column circuit 11[11A and 11B] performs the necessary processes in order, the signals ofodd number columns are sent to the signal processing circuit by theupper vertical driving circuit 13A, and the signals of even numbercolumns are sent to the signal processing circuit 14 by the lowerhorizontal driving circuit 13B (see FIG. 5E). In other words, thesignals of pixels 5 in a pixel column are input to an input terminalwhere the column circuits 11A and 11B face each other. The signals ofthe column circuits 11A and 11B are output to the horizontal drivingcircuits 13A and 13B from an output terminal of a side where the columncircuits 11A and 11B do not face each other.

According to the solid-state imaging device 1 of the first embodiment,the center portion of the pixel unit 6 of the first semiconductor chip 2is connected to the second semiconductor chip 3, and the wiringresistance of the vertical signal line 10 becomes identical for thesignal of any one signal in the upper and lower portions of the pixelunit 6. Compared with the general configuration where pixel signals arecollected from the terminal of the vertical signal line to the columncircuit, in the first embodiment, the maximal length of the verticalsignal line 10 is halved until signals enter the column circuit 11. Forthis reason, in this embodiment, the shading caused by the voltage dropis halved due to the wiring resistance of the vertical signal line 10.In addition, the shading is vertically symmetric with the center portionof the pixel unit 6 as a border and therefore is not easily observed.For example, if the upper half portion of the image is “light (shade)”,the lower half portion becomes “light (shade)”, thereby preventing theshading from standing out.

As described above, in the first embodiment, it is possible to decreasethe voltage drop in the vertical signal line 10 and to decrease shadingcaused by the voltage drop. In addition, when being applied to a camera,an image region corresponding to the periphery of the imaging lens isgenerally dark and is generally corrected in a circuit system. As theshading of the image is vertically symmetric, the correction may beeasily performed. In this embodiment, it is possible to improve theimage quality by enhancing the shading.

In addition, since the maximal voltage drop is halved by the wiringresistance of the vertical signal line 10, this contributes to ensuringa voltage margin or lowering the voltage. Here, the voltage margin meansroom for the operation voltage of a pixel circuit to linearly outputsignals up to a saturation signal, room for the voltage to match anoutput range of the pixel with an input range of the column circuit, orthe like. The dynamic range of the voltage margin may widen as much ifthe process is changed to increase the amount of charges handled. Sincethe width d1 of the column circuit 11 corresponds to the width d2 of twopixel columns, the column circuit 11 may be easily made.

In this embodiment, the first semiconductor chip 2 having the rear-sideincident type pixel unit 6 is mounted in a flip-chip manner to thesecond semiconductor chip 3 while the wiring of the pixel 5 is at alower side, and therefore it is possible to implement the solid-stateimaging device without influencing light receiving or photoelectricconversion.

3. Second Embodiment Example of the Solid-State Imaging Device

FIGS. 6 to 7B show a second embodiment of the solid-state imaging deviceaccording to the present disclosure. This embodiment is a rear-sideincident type CMOS solid-state imaging device, and FIGS. 6 to 7B areschematic views.

In a solid-state imaging device 31 according to the second embodiment,as shown in FIG. 6, a first substrate 32 having a pixel unit in which aplurality of pixels converting physical quantities into electric signalsare arranged in a two-dimensional shape and a second substrate 33 havingcolumn circuits are laminated and electrically connected to each otherthrough a connection portion 4. Hereinafter, the first substrate 32 willbe called a first semiconductor chip, and the second substrate 33 willbe called a second semiconductor chip. In addition, the connectionportion 4 will be called a micro bump. In other words, the firstsemiconductor chip 32 includes, as shown in FIG. 7A, a pixel unit 6 inwhich a plurality of rear-side incident type pixels 5 are arranged in atwo-dimensional shape, and a vertical driving circuit 7. The firstsemiconductor chip 32 becomes a so-called rear-side incident type CMOSimage sensor chip. The second semiconductor chip 33 is, as shown in FIG.7B, configured by forming a column circuit 11, a control circuit 12,horizontal driving circuits 13 [13A and 13B], and a signal processingcircuit 14 corresponding to an output circuit. The first semiconductorchip 32 is mounted in a flip-chip manner to the lower secondsemiconductor chip 33 through the micro bump 4 to configure thesolid-state imaging device 31.

In this embodiment, pixels 5 in two rows are read simultaneously. In thepixel unit 6 of the first semiconductor chip 32, two vertical signallines 10 [10A and 10B] are arranged for one pixel column, so that thefirst vertical signal line 10A is connected to odd number pixel rows andthe second vertical signal line 10B is connected to even number pixelrows. The column circuit 11 of the second semiconductor chip 33 has awidth d3 identical to the width d4 of the pixel column (d3=d4), and isarranged as much as two times of the pixel columns corresponding to thenumber of the vertical signal lines 12. The column circuits 11 arearranged as much as the number of the pixel columns in the horizontaldirection respectively to the upper and lower ends in the verticaldirection. In other words, the numerical relation between the pixelcolumns of the pixel unit 6 and the column circuits 11 becomes 1:2.

The column circuit 11A at the upper end is connected to the firstvertical signal line 10A connected to the pixels 5 in odd number rowsamong the pixel columns. The column circuit 11B at the lower end isconnected to the second vertical signal line 10B connected to the pixels5 in even number rows among the pixel columns. The column circuit 11A atthe upper end and the column circuit 11B at the lower end are arrangedto be dislocated in the horizontal direction as much as a half pitch ofthe pixel column. The column circuit 11A at the upper end and the columncircuit 11B at the lower end are arranged to face each other so thattheir input terminals (portions corresponding to the micro bump 4) faceeach other.

In addition, the input terminal of each column circuit 11A and 11Blocated near the center and the center portion of the vertical signallines 10A and 10B of the pixel unit 6 are electrically connected throughthe micro bump 4. The center portion of the first vertical signal line10A and the input terminal of the column circuit 11A at the upper endare connected through the micro bump 4, and the center portion of thesecond vertical signal line 10B and the input terminal of the columncircuit 11B at the lower end are connected through the micro bump 4.

Other configurations are identical to those illustrated in the firstembodiment, and therefore the corresponding component will be designatedby the same reference symbol and not described again.

FIGS. 8A to 8E show operations of the solid-state imaging deviceaccording to the second embodiment, namely the flow of signals from thepixel. In the pixel unit 6 of the first semiconductor chip 32, signalsare read by the first and second vertical signal lines 10A and 10B inthe downwards order for every two pixel rows. The signals of upper-halfpixels 5 of the pixel unit 6 pass the first and second vertical signallines 10A and 10B in the order from the first and second pixel rows totwo of m−1^(th) and m^(th) pixel rows (see FIGS. 8B and 8D), and areinput to the column circuit 11 of the second semiconductor chip 33simultaneously through the micro bump 4 near the center of the pixelunit 6 (see FIG. 8E). Here, the signals of the pixels 5 of odd numberrows are input to the column circuit 11A at the upper end, and thesignals of the pixels 5 of even number rows are input to the columncircuit 11B at the lower end. The column circuits 11A and 11B in whichthe signals of two pixel rows are simultaneously input perform necessaryprocess in order so that the signals in the odd number rows are sent tothe signal processing circuit 14 by the horizontal driving circuit 13Aat the upper side and the signals in the even number rows are sent tothe signal processing circuit 14 by the horizontal driving circuit 13Bat the lower side. In other words, the signals of the pixels 5 of twopixel rows are input to the input terminals of the column circuits 11Aand 11B which face each other. The signals of the column circuits 11Aand 11B are output from the output terminals of the column circuits 11Aand 11B, which do not face each other, to the horizontal drivingcircuits 13A and 13B.

According to the solid-state imaging device 31 of the second embodiment,since the number of column circuits 11 is twice the number of the pixelcolumns, it is possible to increase the processing rate by approximatelydouble compared with the first embodiment. Since the load capacity ofthe vertical signal line 10 [10A and 10B] is substantially halved, inthe case where a reading rate is rate-controlled by the pixels, theprocessing rate may be further increased by approximately double.

Besides, the same effects as obtained in the first embodiment may beobtained. In other words, since the first semiconductor chip 32 isconnected to the second semiconductor chip 33 near the center of thepixel unit 6, the wiring resistances of the vertical signal lines 10[10A and 10B] are identical for any signal of the upper and lowerportions of the pixel unit 6. Compared with the general configurationwhere pixel signals are collected from the end of the vertical signalline to the column circuit, in the second embodiment, the maximal lengthof the vertical signal lines 10 [10A and 10B] is halved until thesignals enter the column circuits 11 [11A and 11B]. For this reason, inthis embodiment, the shading caused by the voltage drop is halved due tothe wiring resistance of the vertical signal line. In addition, theshading is vertically symmetric with the upper and lower portion of thepixel unit 6 and therefore is not easily observed. As described above,in the second embodiment, it is possible to decrease the voltage drop inthe vertical signal line 10 and to decrease shading caused by thevoltage drop. Therefore, it is possible to improve the image quality byenhancing the shading.

In addition, since the maximal voltage drop is halved by the wiringresistance of the vertical signal lines 10 [10A and 10B], thiscontributes to ensuring a voltage margin or lowering the voltage. Thedynamic range of the voltage margin may widen as much if the process ischanged to increase the amount of charges handled.

Even in the second embodiment, since the first semiconductor chip 32having the rear-side incident type pixel unit 6 is mounted in aflip-chip manner to the second semiconductor chip 33 while the wiring ofthe pixel 5 is at a lower side, it is possible to implement thesolid-state imaging device without influencing light receiving orphotoelectric conversion.

4. Third Embodiment Example of the Solid-State Imaging Device

FIGS. 9 to 10B show a third embodiment of the solid-state imaging deviceaccording to the present disclosure. This embodiment is a rear-sideincident type CMOS solid-state imaging device, and FIGS. 9 to 10B areschematic views.

In a solid-state imaging device 41 according to the third embodiment, afirst substrate 42 having a pixel unit in which a plurality of pixelsconverting physical quantities into electric signals are arranged in atwo-dimensional shape and a second substrate 43 having column circuitsare laminated and electrically connected to each other through aconnection portion 4. Hereinafter, the first substrate 42 will be calleda first semiconductor chip, and the second substrate 43 will be called asecond semiconductor chip. In addition, the connection portion 4 will becalled a micro bump. In other words, the first semiconductor chip 42includes, as shown in FIG. 10A, a pixel unit 6 in which a plurality ofrear-side incident type pixels 5 are arranged in a two-dimensionalshape, and a vertical driving circuit 7. The first semiconductor chip 42becomes a so-called rear-side incident type CMOS image sensor chip. Thesecond substrate 43 is, as shown in FIG. 10B, configured by forming acolumn circuit 11, a control circuit 12, horizontal driving circuits 13[13A and 13B], and a signal processing circuit 14 corresponding to anoutput circuit. The first semiconductor chip 42 is mounted in aflip-chip manner to the lower second semiconductor chip 43 through themicro bump 4 to configure the solid-state imaging device 41.

In the pixel unit 6 of the first semiconductor chip 42, a verticalsignal line 10 to which a plurality of pixels 5 are connected is formedcorresponding to each pixel column. Meanwhile, in the secondsemiconductor chip 43, three column circuits 11 [11A, 11B and 11C] aredisposed in the vertical direction. The column circuits 11A, 11B and 11Care respectively arranged in plural in the horizontal direction. Thecolumn circuit 11A at the upper end correspond to every third pixelcolumn of the pixel unit 6, namely a first pixel column, a fourth pixelcolumn, a seventh pixel column, a tenth pixel column, . . . . The columncircuit 11B at the middle corresponds to every third pixel column of thepixel unit 6, namely a second pixel column, a fifth pixel column, aneighth pixel column, an eleventh pixel column, . . . . The columncircuit 11C at the lower end corresponds to every third pixel column ofthe pixel unit 6, namely a third pixel column, a sixth pixel column, aninth pixel column, a twelfth pixel column, . . . .

Each column circuit 11A to 11C is formed with a width d5 equal to thewidth d6 of three columns of the pixels 5 (d5=d6). The column circuits11B and 11C are arranged to be dislocated in the horizontal directionwith respect to the column circuits 11A and 11B at the upper end as muchas one pitch of the pixel column.

The micro bump 4 connecting the column circuit 11A at the upper end tothe vertical signal line 10 of a corresponding pixel column is formed ata location corresponding to the center input terminal in the secondsemiconductor chip 43 of the column circuit 11A at the upper end. Themicro bump 4 connecting the column circuit 11C at the lower end to thevertical signal line 10 of a corresponding pixel column is formed at alocation corresponding to the center input terminal in the secondsemiconductor chip 43 of the column circuit 11C at the lower end. Themicro bump 4 connecting the column circuit 11B at the middle to thevertical signal line of a corresponding pixel column is formed at alocation near the column circuit 11C at the lower end and a locationnear the column circuit 11A at the upper end in turns in the horizontaldirection.

Other configurations are identical to those illustrated in the firstembodiment, and therefore the corresponding component will be designatedby the same reference symbol and not described again.

FIGS. 11A to 11D show operations of the solid-state imaging device 41according to the third embodiment, namely the flow of signals from thepixel. In the pixel unit 6 of the first semiconductor chip 42, signalsof the pixels 5 are read by the vertical signal line 10 in the downwardsorder for every one pixel row. FIGS. 11B and 11D show the flow ofsignals read from the upper portion of the pixel unit 6. The verticallocation of the micro bump 4 connecting the vertical signal line 10 tothe column circuit 11 is dislocated from the center portion of thevertical signal line 10, and the dislocated position varies depending onpixel columns as shown in the figures. In addition, in the upperhalf-portion of the pixel unit 6, as shown in the figures, the signalsof the pixels 5 of the first pixel column, the fourth pixel column, theseventh pixel column, . . . pass the vertical signal line 10 and areinput to the column circuit 11A at the upper end through the micro bump4 near ⅓ location in the vertical direction of the pixel unit 6. Thesignals of the pixels 5 of the second pixel column, the fifth pixelcolumn, the eighth pixel column, . . . pass the vertical signal line 10and are input to the column circuit 11B at the middle through the microbump near ⅓ location and ⅔ location in the vertical direction of thepixel unit 6 in alternate shifts. The signals of the pixels 5 of thethird pixel column, the sixth pixel column, the ninth pixel column, . .. pass the vertical signal line 10 and are input to the column circuit11C at the lower end through the micro bump 4 near ⅔ location in thevertical direction of the pixel unit 6. In addition, among the signalsinput to the column circuits 11A to 11C, the signals of the first pixelcolumn, the second pixel column, the fourth pixel column, the seventhpixel column, the eighth pixel column, the tenth pixel column, . . . aresent to the signal processing circuit 14 by the horizontal drivingcircuit 13A at the upper end. The signals of the third pixel column, thefifth pixel column, the sixth pixel column, the ninth pixel column, theeleventh pixel column, and the twelfth pixel column . . . are sent tothe signal processing circuit 14 by the horizontal driving circuit 13Bat the lower end.

In regard to reading of signals of lower-half pixels 5 of the pixel unit6, as shown in FIGS. 11C and 11D, though not described in detail, thesignal of pixels 5 of each pixel column passes the vertical signal line10 and is input through the same micro bump 4 as above to thecorresponding column circuits 11A to 11C. In addition, the signalprocessed by each column circuit 11A to 11C is sent to the signalprocessing circuit 14 by the horizontal driving circuits 13A and 13B.

According to the solid-state imaging device 41 of the third embodiment,the signal of each pixel 5 is input through the micro bump 4 to thecolumn circuit 11 at a middle location near ⅓ or ⅔ of the verticalsignal line, though it is not the center portion of the vertical signalline 10. For this reason, the wiring resistance of the vertical signalline 10 is decreased compared with a general solid-state imaging device,resulting in decreasing shading caused by a voltage drop due to thewiring resistance. Therefore, it is possible to improve shading andenhance image quality.

Besides, the same effects as obtained in the first embodiment may beobtained. In other words, this contributes to ensuring a voltage marginor lowering the voltage. If the voltage margin is used for increasingthe amount of charges handled, the dynamic range may widen as much. Inaddition, since the width d5 of the column circuit 11 corresponds to thewidth d6 of three pixel columns, it is easy to produce the columncircuit 11.

In this embodiment, since the first semiconductor chip 2 having therear-side incident type pixel unit 6 is mounted in a flip-chip manner tothe second semiconductor chip 3 while the wiring of the pixel 5 is at alower side, it is possible to implement the solid-state imaging devicewithout influencing light receiving or photoelectric conversion.

Modified Examples

Modified examples common to the first to third embodiments as above willbe described.

In the case where the micro bump 4 cannot help being made with adiameter greater than the width of the column circuit 11, neighboringmicro bumps 4 may be arranged in a zigzag shape.

Since the horizontal driving circuits 13 [13A and 13B] have a highdriving frequency and generate much heat and noise, it is preferablydisposed at an end side of the second semiconductor chip, particularlyat a location not overlapping with the first semiconductor chip or alocation not overlapping with the pixel unit.

Even though the first semiconductor chip and the second semiconductorchip are connected using the micro bump 4 in the above example, bothsemiconductor chips may be connected using another connecting method.For example, as shown in FIG. 12, the wirings 51 and 52 of the firstsemiconductor chip 2 (32, 42) and the second semiconductor chip 3 (33,43) may be compressed so that the wirings 51 and 52 of eachsemiconductor chip 2 (32, 42) and 3 (33, 43) are directly connected.

Even though it has been illustrated that the solid-state imaging deviceuses electrons as signal charges in the above case, the presentdisclosure may also be applied to a case where the solid-state imagingdevice uses holes as signal charges.

5. Fourth Embodiment Example of Electronic Equipment

The solid-state imaging device according to the embodiment of thepresent disclosure may be applied to electronic equipment such ascameras having the solid-state imaging device, camera-embedded portabledevices, and other devices having the solid-state imaging device.

The electronic equipment according to this embodiment includes asolid-state imaging device, an optical system for leading incident lightto the solid-state imaging device, and a signal processing circuit forprocessing an output signal of the solid-state imaging device as basicconfiguration, wherein the solid-state imaging device is configured byusing the solid-state imaging device of the embodiment as describedabove.

FIG. 13 shows an embodiment in which the present disclosure is appliedto a camera as an example of the electronic equipment. The camera 61according to this embodiment includes an optical lens group (opticalsystem) 62, a solid-state imaging device 63, a DSP (Digital SignalProcessor) 64, a frame memory 65, a central processing unit (CPU) 66, adisplay device 67, a recording device 68, an operation system 69, apower source system 70, and so on. Among them, the DSP 64, the framememory 65, the CPU 66, the display device 67, the recording device 68,the operation system 69 and the power source system 70 are connected toa common bus line 71.

The optical lens group 62 leads an image light (incident light) from asubject to an imaging surface (a pixel array unit: a pixel unit) of asolid-state imaging device 63. To the solid-state imaging device 63, anyone of the solid-state imaging devices according to the aboveembodiments is applied. The solid-state imaging device 63 converts theimage light formed on the imaging surface by the optical lens group 62into electric signals for each pixel. The DSP 64 controls thesolid-state imaging device 63 and receives signals therefrom to generatean image signal. The frame memory 65 is a memory used for temporarilystoring the image signal processed by the DSP 64.

The display device 67 displays the image signal output as a processingresult of the DSP 64. The recording device 68 records the image signalon, for example, a magnetic tape, a magnetic disk, an optical disc orthe like. The operation system 69 is used for operating the camera. Thepower source system 70 supplies power to drive the solid-state imagingdevice 63. The CPU controls such operations.

The present disclosure may take a camera module form in which theoptical system 62, the solid-state imaging device 63, the DSP 64, theCPU 66, the frame memory 65, the power source system 70 and so on aremodulated.

The present disclosure may configure a camera-embedded portable devicehaving such a camera module, for example representatively a cellularphone.

In addition, the present disclosure may be configured as a module havingthe modulated imaging function as above, a so-called imaging functionmodule. The present disclosure may configure electronic equipmentequipped with such an imaging function module.

If the electronic equipment 61 such as a camera according to the fourthembodiment is used, in the solid-state imaging device, since the voltagedrop caused by the wiring resistance of the vertical signal linedecreases when a signal of a pixel is read, it is possible to improveimage quality, for example improving the shading caused by the voltagedrop. Therefore, it is possible to provide high-quality electronicequipment.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2010-252587 filed in theJapan Patent Office on Nov. 11, 2010, the entire contents of which arehereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. An imaging device comprising: a first substrate including: a pixel array comprising a plurality of pixels that respectively output electric signals, the plurality of pixels arranged in columns and rows, and a plurality of vertical signal lines that respectively convey the electric signals in a first direction; and a second substrate including a plurality of column circuits respectively arranged corresponding to columns of the plurality of pixels, wherein the first substrate and the second substrate are laminated and electrically connected to one another through a connection portion, and respective ones of the column circuits are configured to process the electric signals and convey the processed electric signals in a second direction opposite to the first direction.
 2. The imaging device according to claim 1, wherein the first substrate includes a driving circuit coupled to at least one of the plurality of pixels through at least one of a plurality of horizontal signal lines.
 3. The imaging device according to claim 2, wherein the driving circuit is configured to output a signal to at least one of the plurality of pixels.
 4. The imaging device according to claim 2, wherein the driving circuit is configured to drive at least one of the plurality of pixels.
 5. The imaging device according to claim 2, wherein the second substrate includes a control circuit coupled to the driving circuit.
 6. The imaging device according to claim 5, wherein the control circuit is configured to control the driving circuit.
 7. The imaging device according to claim 1, wherein at least one of the plurality of column circuits includes at least a portion of an analog to digital converter.
 8. The imaging device according to claim 1, wherein the connection portion comprises a plurality of bumps.
 9. The imaging device according to claim 1, wherein the first substrate includes a first wiring, and the second substrate includes a second wiring coupled to the first wiring.
 10. The imaging device according to claim 1, wherein at least one of the plurality of pixels includes a photodiode, a transfer transistor, a reset transistor, an amplifier transistor, and a select transistor.
 11. The imaging device according to claim 1, wherein the second substrate includes a horizontal driving circuit.
 12. The imaging device according to claim 1, wherein two signal lines of the plurality of signal lines are provided for a corresponding column of pixels in pixel array.
 13. The imaging device according to claim 1, wherein respective ones of the plurality of pixels are a rear-side incident type.
 14. The imaging device according to claim 1, wherein the second substrate includes a current source coupled to at least one of the signal lines.
 15. An imaging device comprising: a first substrate including: a pixel array comprising a plurality of pixels arranged in columns an rows, at least one of the plurality of pixels configured to output an electric signal, and a plurality of signal lines, at least one of the vertical signal lines configured to convey the electric signal in a first direction; and a second substrate including a plurality of column circuits respectively arranged corresponding to columns of the plurality of pixels, at least one of the plurality of column circuits configured to process the electric signal and convey the processed electric signal in a second direction opposite to the first direction, wherein, the first substrate and the second substrate are laminated and electrically connected to one another through a connection portion.
 16. The imaging device according to claim 15, wherein the first substrate includes a driving circuit coupled to at least one of the plurality of pixels through at least one of a plurality of horizontal signal lines.
 17. The imaging device according to claim 16, wherein the driving circuit is configured to output a signal to at least one of the plurality of pixels.
 18. The imaging device according to claim 16, wherein the driving circuit is configured to drive at least one of the plurality of pixels.
 19. The imaging device according to claim 16, wherein the second substrate includes a control circuit coupled to the driving circuit.
 20. The imaging device according to claim 19, wherein the control circuit is configured to control the driving circuit.
 21. The imaging device according to claim 15 wherein at least one of the plurality of column circuits includes at least a portion of an analog to digital converter.
 22. The imaging device according to claim 15, wherein the connection portion comprises a plurality of bumps.
 23. The imaging device according to claim 15, wherein the first substrate includes a first wiring, and the second substrate includes a second wiring coupled to the first wiring.
 24. The imaging device according to claim 15, wherein at least one of the plurality of pixels includes a photodiode, a transfer transistor, a reset transistor, an amplifier transistor, and a select transistor.
 25. The imaging device according to claim 15, wherein the second substrate includes a horizontal driving circuit.
 26. The imaging device according to claim 15, wherein two signal lines of the plurality of signal lines are provided for a corresponding column of pixels in the pixel array.
 27. The imaging device according to claim 15, wherein respective ones of the plurality of pixels are a rear-side incident type.
 28. The imaging device according to claim 15, wherein the second substrate includes a current source coupled to at least one of the signal lines.
 29. An electronic apparatus comprising: an optical system; and an imaging device comprising: a first substrate including a pixel array comprising a plurality of pixels arranged in columns an rows, at least one of the plurality of pixels configured to output an electric signal, and a plurality of vertical signal lines, at least one of the vertical signal lines configured to convey the electric signal in a first direction, and a second substrate including a plurality of column circuits respectively arranged corresponding to columns of the plurality of pixels, at least one of the plurality of column circuits configured to process the electric signal and conveys the processed electric signal in a second direction opposite to the first direction wherein the first substrate and the second substrate are laminated and electrically connected to one another through a connection portion.
 30. The electronic apparatus according to claim 29, further comprising: a digital signal processor that processes an output of the imaging device; and a display device that displays an output of the digital signal processor. 